Refrigeration apparatus



y 1943 T. s. SAFFORD REFRIGERATION APPARATUS FiledOct. 9, 1936 3Sheets-Sheet l control that the or with her ice for purpose Patented May18, 1943 UNITED STATES PATENT OFFICE -REFRIG'ERATION APPARATUS Truman S.Safiord, Riverside, Conn. Application October 9, 1936, SerialNo..104,840

'1 9. Claims.

This invention relates to a device fol-automatic defrosting ofrefrigerators, andmore particularly to such a device which is adaptedto'control the refrigeration, e. g., by cutting off the supply ofrefrigerant, so 'that'frost which may have accumulated upon therefrigeratin surfaces maybe allowed to melt away, but whichwill-exercise such control only at'times when rapid refrigeration isordinarily not required.

Since the introduction many years ago of artificial refrigeration, theaccumulation of frost 'upon therefrigerating surfaces has presented oneof the most annoying andever present problems. Numerous methods ofdefrosting by heating or dissolving the frosthave been suggested and tosome extent have been used, but such methods have been manuallycontro-lled'and have been dependenttherefore upon the care andwatchfulness of the operator. In domestic refrigerators the cooling unitis often hidden behind an enameled iron screen, and'the operator, oftena domesticservant understanding little or nothing of the operation ofthe refrigerator, may allow the frost to collect for weeks oreven'months before the defrosting is carried out.

It has alsobeen proposed to make defrosting automatic by widening thegap between the on and off temperatures'of-the thermostatic control.Thus the temperature at which the refrigeration is begun in' eachcycleor in one of a series of cycles-may be sufficiently hig to ensurethat the frost will bemelted before a new cycle or a new series thereofis-initiated. While this'sug- 'gestion mayovercome the objection tomanual control will be operated too infrequently, it introduces a moreserious objection from thepoint of view of the manufacturer'and userofdomestiorefrigerators' that it'may at any time leave a hostess in thelurch with no ice cubes cream and frozen desserts melted. It is anobject of the present invention to prowide-an automatic defrostingcontrol, which will require no'attention, and will'ensure the tho-rougliand'frequent elimination of frost, with little "or no likelihood offailing to provide adequate refrigeration -at-times when it is neededpurpose.

In the accompanying drawings for any I have shown, of illustration, anumber of embodiments myinventionby which this object and other objectsmaybe accomplished.

Fig. l is a front elevation of a domestic refrigerator with the doorremoved to disclose the positionin or parts used. in-my invention;

.g. 'Z'is a detailed cross sectional viev taken on line scale;

Fig. 3 is a longitudinal vertical sectional view of a switch used in oneembodiment ofinyinvention;

Fig. i is a vertical cross sectional view line 4-4 of Fig. 3;

Fig. 5 is a'view in side elevation of a detail which may replace aportion of the device illustrated in Fig. 2;

Fig. 6 is a sectional view be used in place of thatthat of .Fig. 2';

Figs. 7 to 9 inclusive'are circuit diagrams illustrating variousembodiments of my invention;

Fig. 10 is a fragmentary view of a refrigerator box showing anothermodified form of my invention in position;

Fig. 11 is a fragmentary view in horizontal sec- 2-2 of Fig. 1 and shownonan enlarged taken on of a device which may illustrated in Fig.5 or

tion of the same embodiment as shown in Fig. 10;

Figs. 12 and 13 are detail views showing a part of the device of Figs.10 and 11 in different positions of operation;

Fig. 14 is a detail View partly in section-showing the device forholding theswitch mechanism;

Fig. 15 is a fragmentary view similar to the right hand portion of Fig.11 but showing the device after the predetermined delay and with theparts in position to permit defrosting;

Fig. 16 is a fragmentary view partly in vertical section of anotherembodiment of my invention;

Fig. 17 is a wiring diagram of the embodiment illustrated in Fig. 16;

Figure 18 is a diagrammatic illustration of another modification of. myinvention;

Figure 19 is a detail of the controlling means as used in Figure 18; and

Figure 20 is a detail of a control switch.

In Fig. 1, I have shown adomestic refrigerator of common form having aninsulating box 20, the door of which has been removed to disclose theinterior, a cooling unit 21,- a central partition 22,

and shelves 23. A clock 24, advantageously an electric clock operatedfrom the same alternating current power line as the refrigerator motor,may be associated with the refrigerator, and as will be morefullydisclosed hereinafter, this clock may serve as one control in thedefrosting device. It

is .not necessary,-however, that this clock, if used as a defrostingcontrol should have a visible face,

erator in Fig. 1, and the purpose of this as well as its detailedconstruction will be set forth below.

I have said above that one purpose of this invention is to protect thehostess against failure of adequate refrigeration at critical times. Myinvention therefore contemplates the provision of devices which areresponsive to, or may be correlated with, the uses to which therefrigerator is put.

Fig. 2 illustrates the control element of a device which is directlyresponsive to the use of the refrigerator. In this device, an operatingrod 2'! is mounted in a hanger guide 28 secured to the box 23, and ispreferably provided with a cushion buffer 29 on its outer end.

A link 33 is pivoted to the opposite end of the rod 21 and the oppositeend of this link is pivotally connected to the crank 3|, which engages aswitch 32 of the type having a fluent conductive material adapted toflow onto and away from spaced electrodes. This switch is pivotallysupported in hangers 33; and, as shown, the leads to the electrodes 38may serve as the supporting pivots, thus making contact with the members33, which, therefore, may serve as binding posts to connect thesein-leads into the circuit. Thus when the door is open the operating rod21 is released and the fluent conductive switch is allowed to hangvertically from its pivot. When the door is closed it pushes the rod 21and through the linkage 30-3! the switch is pushed upwardly to theposition shown in Fig. 3. It is desirable to provide a spring on the rod21 between the support 28 and the buffer 29 to assist in restoring theparts to the position shown in Fig. 2 whenever the door is opened.

The switch which I use for this purpose is advantageously one of specialdesign as shown in Figs. 3 and 4. A body of fluent conductive material35 is carried in a vessel 36, commonly a sealed glass tube, and thevessel is provided with a baffle 01' dam 31 between the end having theelectrodes 38 and the opposite end. Near the bottom of this dam is anarrow orifice, so related to the volume of the fluent conductivematerial as to require a predetermined time for it to flow therethrough,and at the top of the dam is an open space sufliciently large to allowthe entire body of fluent material to flow back over the damsubstantially instantaneously when the vessel is tipped down. Preferablythe dam is slanted as shown in the drawings to facilitate the returnflow over the dam. The fluent material may be an electrolyte, especiallyin the case of alternating current and especially where it controls a oI relay circuit rather than the main motor circuit,

e. g., as shown in Figs. '7 and 9 of the drawings. The fluent materialmay also be a fine metallic sand or sprayed metal similar to shot but ofvery much finer grain.

The electrodes 38, in the preferred form of the invention are bent overso that they pass out through the walls of the vessel along the axis oftilting. The external parts of the electrode inlead wires may thereforeserve as trunnions to carry the fluent conductor switch, and in order toprovide electrical contact, these electrode wire trunnions arepreferably mounted in hangers 33 connected into the circuit so that theyserve also as binding posts for the electrodes 38. parts are insulatedfrom the box 20 and should also be insulated from the rod 2! by aninsulating link 30 or crank 3|.

In the use of the device just described, the opening of the door allowsthe rod 27 to move These outwardly and the fluent conductor switch totilt downwardly to the position shown in Fig. 2. In this position, somuch of the mass of fluent conductive material as has passed under thedam 3! falls down over it into the then lower end of the vessel 36. Uponthe reclosing of the door the vessel 33 is again raised to the positionshown in Fig. 3, whereupon the fluent conductive material is dammedbehind the dam 31 and allowed to flow only very slowly through theorifice to the other end of the vessel, until it finally reaches thelevel of the electrodes 38 and closes the circuit between them. In thisway a delay of any required duration may b interposed between the lastopening of the refrigerator and the shutting dOWn for defrosting, andthus sufficient time may be allowed for freezing ice cubes, etc., or thetime interval may be adjusted so that it will be greater than will occurat any time during a normal working day, and thus defrosting will occurnormally during the small hours of the morning when it cannot interferewith the various uses of the refrigerator.

When the device just described is combined with a, clock or otherchronometer device, e. g., as shown in Figs. 1 and '7, and the fluentconductive material is an electrolyte a third electrode 5| isadvantageously provided. This electrode is arranged so that it justtouches the stream of conductive material which flows under the dam 37and along the trough d2, so that after the conductive material has madecontact with the electrodes 38 and as the last of it flows along thetrough 42, a contact will be established temporarily between theelectrode 3% and the electrodes 33.

In Fig. '7, I have shown a wiring diagram of a circuit which may be usedwith the defrosting controls which have been thus far described. Theclock 24 in this case is provided with a contact segment 45 and arotating contact arm 45 which preferably makes one revolution eachtwenty four hours. Adjacent the beginning of the contact segment is aswitch 41 normally held open but adapted to be temporarily closed by theaction of the rotating arm 33 on the insulated portion of a bell cranklever which forms the switch 47. At or near the end of the segment 45 isanother bell crank lever, also of insulating material, for operating aswitch 48 normally held closed but opened temporarily by the arm it. Bytemporarily I do not of course intend to imply that there is any shorttime limit upon the operation of these switches, but their work isquickly done and if they are held longer it is merely a convenient wayof operating.

A lead 49 connects the arm 3% with the main line conductor 56, and eachof the switches 41 and 48 is connected to this lead 49 through aparallel circuit portion. The parallel circuit portion which includesswitch 68 also includes thermostat switch 5| associated with therefrigerating unit and adapted to open when the temperature at the outersurface thereof rises above a temperature limit at which defrosting iscomplete. Switch 5! is adapted to close when the said surface is cooledto a temperature at which frost occurs thereon. The switches i? and 48are also adapted to be connected to one of the electrodes 38, the formerdirectly and the latter through the upper contact of the relay 53, andthrough the coil back to the main line conductor 5 1. The relay 53controls the main refrigerator power circuit or the main refrigeratorcontrol circuit by means of the contacts 55.

agar-93,49

lThercontact-ssegment 45: is ;connected directly :tothethirdrelectrokieM Irof 'the;switch1 32.

.TInT. the. operationxofzuthis "device, the arm 46. is "rotated by the-tclock until it rstrikes .1 the aim Y of the :bell icra-nk rswitfch'4"! and thus closes the fi'circnitx'throughfsaid switch l1 :to the:electrodes 38tofithe- 'fluent:con'ductor switch 932. .If the re-:frigerator door is closed :and has been iclose'd ilong enough :to.iallo'w the 'fluent :con'ductor to .close the 'c-ircuit ebetween "theelectrodes 38, the relayi5=3 is iener'gized at once and the 'main re--frigerator5circuitis broken atz55. .Assuming that ftherecis frost'onvthe refrigerating unit, its tem- ;'perature :will :be such ithat thethermostatic switch 551 'will be :rclose'd; and immediately upon theoperation .of .thelrelay $53, the parallel 1eniergizing circuitiwillabe"closed through -the switch 48;.randithesswitchiilp 'lThusit'heirelayarmature will the :heldup *even after the switch T41 is rdropp ed by?theriarm T46.

.Defrostin'gv is.. accor.fipiished by preventingfurther'ref'rigerationxby reason Oft'hecopening df the main circuit at:55 penitence initiated, defrosting *will continue until one of 2 threethings happens. iIn the firstzplace iri'gerator. If ithis :is done, itwill :very .likely mean that thex'icea'trays:mayhave been 5 fresh Il'fil-led with -water or thatfl'a'eonsiderable quantity of .ivarrnzairihas ibeenra dmitted which :will call .forfrnorerapid refrigeration .to.restore tthe :de-

sireditemperature ionpreservationsof the .foods. Opening of the 'doorwill, as described above. break the relay circuit at 32,.andwilltherefore allow fnorm-al 'operation of the refrigerator I once more.after the closixgroflthe fdoor therconductivematerial will agalI1-.-contact with. the electrodes r38. At this time, however, thecircuitmaybeopen at 47 Lby'reason iofthe arm v46 :having passed thefar-nr ofthe=.bell 'crank::switch 47, huttif the arm'f45 is still on the contactsegmentfi the relay circuit willinevertheless "be closed through thesegment fifi :and "the electrode 14 I :and 1 the: stream "ofconductiveii-iquidfi flowing the: trough 42 if the massiof lconductivei'liquid :collected tin the end of .theituhetiifi i hasirisentort-he level of the "electrodes-:38. "Once operated by'this temporarycircuit, the relay :will the held thy" the closing of: thGTCllCLl'lt.thlfl1lgh2thBXSWltChBS43 and I 5!.

someone :may open the re- When i'the specified period has elapsed Thesecond. event ovhich imay causetthe'relay 5,;

to drop itsarrnature aandmestore normal operation: 'ofthe refrigeratoris nthe completion of '7 the defrosting. 'When the tempera tureoi therefrig- I eratin'g surfaces crises above the .freezing "point the'thermo'static switchfii :opens and 'the2relay circuit isrbrokenwhereupon 'normalcoperation" is 'restore'd and 'continuesiuntilthetiappointec chour i is reached again.

'The third event is the end "of -the time allowed for defrosting. It maysometimes 'happen tliat -frozen *dessertsetc, -'or 'ice cubes "may meltf-a little at the'viery end-of the' defrosting period. since these maybe needed early in the morning-or at theend of any other-periodappeinted 'fordefrosting, it maybe desirabletorestorenormal operationeven before the comple- --t-ion otdefrostingnnd beiorethe door-isopened. For this purpose the-switch 43 is provided. This switch-isopened by the passing of the arm-4,

aud t/henopened breaks the i'elay'circuit and oausest'he'dropping of thearmature,

In Fig. 8 I have shown a' similar wiring diagram of a" circuitcontrolled by the-clock-alone. '"I-n "this case the defrosting begins ati the appoi-nted time and continues until-the end :of the 75 apparentifrom "what has already cored Ito .ithe :shaft l t5.

.appointed time unlesssbefore then; theidefrosting is :completed. Thetoperation in this case .by means of the switches 41, 48 and '5twill bereadily been said in connection with Fig. '7.

"Fig. '9;shows a similar circuit diagram of the case where the .circuit.control is entirely by means ofthe door-control, e. 'g.,;as illustratedin Figs. 2 to 5 inclusive, Inthis :case the openi-ngof the-"door :breaksthe relay circuit at 32, :a nddtisronly after-the required delay thatthis circuit'canbere established. Duringzthe normal :daythefrefrigeratorwill beirequently opened, and the'delaynmay be chosen sothat defrosting .willioccurtonlyat night, or the .delaymay besufjficientso .as to. provide time to perform the refrigerationordinarilyrequired after the refrigerator is opened, such as the rapidcooling of thQZbOX' and the'freezing of :water in ice trays.

' .lIn. ;Fi'gs. 5'an'd 6,-TI have shown .two alternative .=typesof:'door controlwhich maybe used'instead "of thatfillustrated in Figs.2; 3 and 4, e. g. in'the circuit shown'in Figurei 9. Theseare-shownpri-'rniarilyito illustrate the widely varying mechanisms which may beusedforthis purpose with- "out departing:fromthescope of my invention. 'lnthedevice toI":F-.ig. 5 the push rod-27 is connected to a gear rackTBD,which through a pinion and ratchet .notshown rotates the shaft 6| towind :the1spring "b2 within the drum 63. Any *imown type'of'overwindprotector may be provided'as for .examplea friction clutch adapted toslipiwhen the "spring is fully wound. The 'gearffidonthe;drum 63 'drivespinion 65 formiingzpart ioi a:suitab1e-clock"w0rk with escape- -mentcit-governor to determinethe required delay and at the end of such delayoperates aswitch or other :defrosting control.

:therein :servesas the-delaying means and at the end :of the delay.allows 'operation of" the defrosting control. The spring .68 pushes theplunger-6'! *to'theleft when the door is opened and a spring 69 receivesand stores up the force ofltherclosing of'the door. A flap valve 'H'pro-'vi'desforirapidamovement of the plungerto the left 'delayedfmovement'in the: other 'direction. :flange 70 "may serve to operate thefdeirostingcontrol device.

When thisformfof :do'or control replaces that showntin Figs. 12, .3 sand4, the closing .of the door pushes thelrod' 2'! so :Las to compress the'The piston' 61 is then slowly driven 'downtheicylinder underinfiuenceof the spring 'Sduntilthe point is reached'atwhich the flange"19: closes .orcoperatesthe: control switch "or otherdefrostingr'controlfdevice. As :soon as the door -istopenedthe-:pressurerxon"spring 69 is relieved ian'd the piston is promptlyforced back under the-influence of the spring :68. Since the flap valveH is iopenedidnring'this return movement,

-the-piston returns'veryiquickly, and thedelay :begins aneWwhenttheidooris: again-closed.

I In :Figs. .lOito 15 inclusive 1 have shownanother'embodimenttof'myinvention. In this case 1 have tprovided1aswitch "I 10 connected directly :into the motor circuit. This switch asbest shown *infiFig. 114 is rotatably mounted on a rod H5 andat theother :endeneaees the collar l'l se- This springis under tension 'sothat it .tends to hold the'switch H0 "member and its holder III in theposition shown in Fig. 12, but permits it to be rotated to the positionshown in Fig. 13.

From the bottom of one of the spring fingers I25 of the holder I I I astud I24 projects laterally beyond the side of the switch III] and intothe path of the member I23 connected to the hollow piston member I28which will be more particularly described below.

A casing I20 in this embodiment of my invention illustrated in thedrawings encloses the switch and air cylinder mechanism and only the rodI I5 and the plunger I22 project through this casing. A buffer blockI35, preferably of soft rubber, is secured to the bottom of the casing,as shown in Figs. 12 and 13 to stop the rotation of the switch III andsupport it in the position shown in Fi 12. Y

The air cylinder delay mechanism comprises a fixed cylinder I33 securedwithin the casing I23. At the inner end of this cylinder I33 is a rentopening controlled by an adjustable valve plug I3I which is constructedto allow an inrush of air but to permit a very slow leakage of airoutwardly from the cylinder.

Within the cylinder I33 is accurately fitted the hollow piston memberI28 and against this presses the spiral spring I32. Within the hollowcylinder I28 is fitted the hollow push rod I21 with its open end inwardand the spring I29 is fitted within both hollow members pressing againstopposite ends thereof respectively. The cam I 23 is secured in thepiston member I23 and has a portion extending into the open slot I33 ofthe push rod member I21 so as to limit its movement out from the hollowpiston member I28.

The spring I32 is chosen just strong enough to push the piston I28 backto the beginning of its stroke when it is released from the pressure ofthe spring I29. The spring I29 is sufficiently strong to drive thepiston I28 against the pressure of the spring I32 to the inner end ofits stroke.

In the operation of this device when the door of the refrigerator box isbeing opened the push rod I21 isreleased and under pressure of thespring I29 immediately moves out from the holow piston I23 to the fullextent permitted by the extension on the cam member I23 and its slotI33. At the same time the spring I32 pushes the piston I28 outwardlyuntil the cam member I23 reaches the end of the slot in cylinder I33.This same movement draws air in through the valve I3I filling the spacewithin the cylinder I33. The cam member thus is moved out from under thestud I24and the switch H0 is allowed to drop into the position shown inFig. 12 in which the fluent conductive material falls over the contactmember and closes the circuit of the motor. Thus normal operation of themotor will continue under control of the usual pressure and/ortemperature control. When the door is closed it contacts the push rodI21 and drives it into the hollow piston I28 compressing the spring I23.The force of the spring I29 causes the piston I28 to move a shortdistance but this movement is limited by the air within the cylinder I33which under compression resists the force of the spring I23. Very slowlythis air is allowed to escapethrough the valve plug 931 until after therequired delay the cam member I23 passes under the stud I24 lifting italong its .cam surface until it reaches the position shown in Figs. 13and 14. In this position the switch is tilted so that the fluentconductive material falls away from the contacts and the motor circuitis broken beginning a defrosting period. This defrosting continues andthe motor remains inoperative until one of two conditions occur. If thedoor is open the parts move again to the position shown in Fig. 11, andthe switch is dropped to the position shown in Fig. 12. In thisposition, as already described, the motor becomes operative andrefrigeration begins again. If, however, the door is not opened untildefrosting is complete and the surface of the .cooling unit II4-risesabove freezing temperature then the snap thermostat IIB snaps to a fiatposition pulling the rod H5 toward the left, and pulling the stud I24off of the cam member I23. When this occurs the switch III! drops againto the position shown in Fig. 12, notwithstanding the fact that the camI23 is still in the position shown in Fig. 13. Thus refrigeration canbegin again. When this occurs, of course, the thermostat H6 is cooledand snapped backto the position shown in the Figs. 10 and 11. In orderthat the cam member I23 may pass over the stud I24 when it is thusrestored to the position shown in Figs. 11 and 15 the end I23 of the cammember is pivoted so that it may swing up but not down. Thus when thecam member'- I23 is retracted to the position shown in Fig. 11 it passesreadily over the stud I24 but when moved again to the position shown inFig. 15 it will engage the stud I24 and shift the switch as alreadydescribed.

In this case, as in the cases already discussed above, the delayinterposed by the air cylinder mechanism is advantageously such as topermit freezingof ice cubes or desserts placed in the trays of therefrigerating unit II4.

In Figs. 16 and 17, I have shown another embodiment of my inventionsimilar in operation to that illustrated in Figs. 10-14. In this case-acylinder I43 is supported in a bearing rail I4I on brackets I42 and I43.On the top of the cylinder is a gear rack I44 which meshes with a pinionI45 driving'an escapement or governor,

not shown, through a ratchet mechanism so that it can be quicklyreversed but driven only at a constant slow speed in a forwarddirection.

Within the cylinder I43 is a spring I46 which bears against the end ofthe push rod I41 so that when the push rod is driven into the cylinderthe spring I46 is compressed and energy stored therein. The outer end ofthe push rod I41 has a head I48 having one side positionedto engage thedoor when it is closed and its opposite side engages the spring I49which, when the door is open moves the push rod -I41 and through'it thecylinder I40 to the left to the full extent of their permitted movement.I g

.In linewith the end of the cylinder- I;40 ;and at the end of its inwardstroke is a switch mechanism I53. In the drawing this is.-shownenclosedin a casing, and of the working parts only the push rod I5! isshownextending from the casing. This push rod I5I is engaged by the end ofthe cylinder I40 as it approaches the end of its stroke and is pushedinwardly to open the switch and render the motor inoperative and therebyto initiate a defrosting period. As soon as the door is open, however,thecylinder I40 and the push rod I41 immediately move to the left to thefull end of their permitted stroke. When the door is re-closed the pushrod I41 is driven'to the right to the end of its stroke, while thecylinder I4!) is restrained by the escapement mechanism I65 and,therefore, the spring I46 is compressed and a delayperiod begun. As theescapement operates under the drive of the spring I46 the cylinder I40moves slowly towards'the right until it again contacts the push rod II,opens the switch and initiates another defrosting period.

As shown in Fig. 17, which shows a modification of the embodiment shownin Figures to inclusive a thermostat I55 is provided responsive to thetemperature of a surface to.be defrosted. This thermostat is shown asnormally contacting with a spring contact I55 to close the circuitthrough the switch I59 to the motor. Thus when the switch is open themotor circuit is opened and a defrosting period begins. If, however,defrosting is completed before the door is reopened and the surface towhich the thermostat is responsive rises above the temperaturecorresponding to complete defrosting, then the thermostat contacts withthe second contact I56 and thereby closes a shunt across the switch I58and begins the normal operation of the motor for renewed refrigeration.In this circuit the thermostat I 54 is shown as controlling the normaloperation of the motor M, i. e., when the temperature is suificientlylowered by operation of the refrigerating mechanism the thermostat opensthe circuit at the contact I55. It will be understood, however, that anyof the usual controls may be included in the motor circuit and thisthermostat IE4 serves only for initiating a renewed refrigerating cycleafter completion of the defrosting.

In Figures l8, l9 and I have shown ann other embodiment of my invention.In this case the delay is determined by the operation of therefrigerating device. A rotary contact member 166 is driven throughsuitable reducing gears so that one rotation of the disc I88 representsa sufficient operation of the refrigerating device .to freeze ice cubesor a dessert in the trays of the cooling unit. In the present instance Ihave shown a worm wheel Edi driven from a worm iii-2 on the shaft of themotor I63 which operates the refrigerating device, not shown. The wormwheel I6I is in turn connected to a second worm I64 which drives theworm wheel 555 on the shaft- H35. At its opposite end the shaft I56carries rotatably thereon the contact disc H vand between the worm wheelI85 and the disc hit is splined as shown at it? for reception of .aclutch 168 the hub of which engages the spline portion of the shaft andthe face of which frictionally engages the disc I63. The clutch ispressed into engagement by the spring Ill] and is connected fordisengagement by the push rod ill mounted in the brackets I12 andhaving. a

head I73 which engages some part on or connected to the door. Thus,whenever the door is open the clutch W8 is released by force of thespring I14 acting thrcughthe push rod Ill and the contact disc I60 isrotated to the beginning of its cycle by means of the spiral spring I15which en ages its hub.

As shown inFigure 19, the disc Itii is made of conducting material withan insert I16 of insulating material. The brushes I71 and I78 connectedinto the motor circuit contact with the rim of this disc I66. Thus themotor continues to operate from the beginning of its cycle until theinsulating insert comes under one of the brushes. When this occurs themotor circuit is broken and a defrosting cycle begins. In this ,case ,nomeans is shown for automatically ter operated by said minating thedefrosting cycle and it will continue untilthe dooris next opened. Itwill be under? st d, oweve tha n, th s casea nth othe c e i ust ate nora refrig r on ca .b a ai in i e crm tat a l lc a br hue ins th ou h. thw t h. l'ifi ract ras sh in Fi -i Bec u e o th d n .o ami e h n thinsulating insert passes under one of the brushes, a is prefer bl in thedis athei t he the brushes I17 and I78 contact.withit should be mm rsein 1. or -a hc l o ct ains ar in -.Viher thi s o a t b a m r s it h a euse f x m e. as u t e e in e- "2 In th scas h me c y itch am unted-0 aivo e h l I eh o lows th cont u o th d of e-c i I504 Throughout thepredetermined cycle the switch is held in closed circuit position, butwhen the follower portion .of the holder reaches the indented portion ofthe disc Ififia the switch drops to an open circuit position and thedefrosting period begins. 0f course, inthis instance the conductorsvterminate near the left hand, end ,of the switch shown in Figure,20 inextremities which. may be bridged by the mercury, the con.- ductors.being otherwise suitably insulated from the mercury within the mercurycontaining tube.

Although in theabove. I have described a preferred form of vmyinventionand several modifications thereof, it is to be understood that these aregiven only by way. of illustration of the numerousways in which theinvention, may be embod I s d of sh t n cfi r frig ra i n e tirely fo pei dt fr gerato -may erely. .be set dur n at pe iod t m tain a tempeature slightly abovefreezing. Thus the closingof the refrigerator doormayset the control for rapid freezing, and at the end ,of adelaysuflicient to meet normal demands following upon ,the opening ofthe refrigerator,.the control may be shifted so. as togna-intain the,refrigerating surfaces at or slightly above the freezing point.

This application is a continuation in p rt of y prior o e ne l cat en...61 220 l J i 0, 19 Q What, I claim is:

e ro tin refr gera comprising an i sulating box having :a door, arefrigerating unit therein of the type adapted automatically to m nta heempe atm' -norm i t bo within predetermined limits, supplementaryelectricalmeans for controlling the supplyof refri r m t sa ef ieratineun t s as t permit me tin o fr ere r m. sa me comprising a relay,a chronometer device, a switch 7 chronometer device, ata predeterminedtimeto close momentarily the relay circuit, a .parallelcircuit portionaround said chronometer operated switch including in series a contactclosed by the armature of the relay,,a switch normally closed .but.opened by, said chro- ,.n m e i .a ,amr det ined. time -af-ter t e; csms-and openine o the fi s a e ..cl r0- nometer ;,oper ated,switch, land a thermostatic switch responsive to the temperature of. said.surfaceto. be defrosted and adapted .to. be;opened when the temperatureof said'surface rises above the freezing vpoint, and means for delaying.the

operation of said relay until a substantial. time has elapsed afterdoor.

the opening of the refrigerator 2. A defrosting refrigerator as definedin claim of the relay comprises a switch in the relay circuit, means foroperating the switch having a substantial lost motion operation beforeit comes into effective-operating relation to said switch, means forregulating the speed of said lost motion operation, and means responsiveto opening of the refrigerator door for resetting said switch operatingmeans to the beginning of its lost motion.

3. A defrosting device for a refrigerator having an insulated box with adoor and a refrigerating unit, which comprises means for controlling theoperation of the refrigerating unit temporarily to permit melting offrost, means for operating said controlling means having a substantiallost motion operation before it comes into effective operating relationto said controlling means, means for regulating the speed of said lostmotion operation, and means responsive to opening of the refrigeratordoor for resetting said operating means to the beginning of its lostmotion.

4. A defrosting refrigerator as defined in claim 1 in which the meansfor delaying operation of the relay comprises a body of fluent material,a barrier having a narrow orifice, means for controlling a circuitresponsive to flow of a substantial volume of said fluent materialthrough said orifice and means for restoring said fluent material to theopposite side of said barrier when the door is opened.

5. A device for automatic defrosting of refrigerators which comprisesmeans for temporarily interrupting refrigeration, means responsive tothe opening of the refrigerator door to prevent interruption ofrefrigeration by the interrupting means during a substantial delay afterthe opening of said door, a chronometer device, and means associatedwith said chronometer device for limiting the operation of theinterrupting means to a predetermined time when rapid refrigeration isnormally not required.

6. A device as defined in claim 5 which includes means responsive tosaid second-mentioned means for operating said interrupting means at theend of the delay if the means associated with the chronometer device isset to permit such op eration, and means associated with the chronometerdevice for operating said interrupting means at'the predetermined timeif the delaying means is set to permit such operation, each of saidoperating means being adapted to operate said interrupting means onlymomentarily, and means associated with said interrupting means forholding the interrupting means in operated position after said momentaryoperation has ceased.

'7. A device for automatic defrosting of refrigerators which comprisesan electrical circuit adapted to control the refrigeration, a relayadapted to control said circuit so as temporarily to prevent furtherrefrigeration, a chronometer device, a switch in the energizing circuitof said relay controlled'by said chronometer device so as to operate therelay at a predetermined time when rapid refrigeration is not required,a parallel portion of the relay circuit adapted to be closed by therelay armature so as to keep it energized once the relay has beenoperated, and a switch in said parallel circuit portion adapted to beopened at a given time when rapid refrigeration is likely to be requiredwhereby to release said relay and restore normal control ofrefrigeration.

'8. A device as defined in claim '7 which further includes athermostatically operated switch adapted to open said relay circuit whena temperature is reached at which defrosting is complete, and thereby torestore normal control ofrefrigeration.

9. A device for automatically defrosting refrigerators which comprisesmeans for interrupting refrigeration, means for momentarily operatingsaid interrupting means at atime when rapid refrigeration normally isnot required, means for holding said interrupting means when thusoperated, means responsive to completion of the desired defrosting forreleasing said interrupting means so as topermit renewed refrigeration,and means for releasing the interrupting means at the end of an intendedperiod ofdefrosting, whether or not the defrosting is complete.

10. A device for automatic defrosting of refrigerators which comprisesan electrical circuit adapted to control the refrigeration, a relayadapted to open said control circuit temporarily to prevent furtherrefrigeration, means in the energizing circuit of said relay adapted toclose said relay circuit at times when rapid refrigeration is notrequired, and a thermostatic means responsive to the temperature of arefrigerating surface which is to be defrosted and adapted to open saidcircuit when the temperature of said surface rises above the freezingpoint,

11. The combination with an automatic refrigerator comprising arefrigerating device having a cold unit, a freezing container associatedtherewith, and an insulated box enclosing and cooled by the cold unit ofmeans for temporarily interrupting operation of the refrigerating deviceduring a period adapted to permit melting of frost accumulated on thecold unit, and means responsive to an operation necessary to the placingof liquid in said container in such position as to be frozen by thecold-unit, which means is adapted to delay the effect of saidinterrupting means during a normal freezing period following saidoperation. 7 r r 12. A device for automatic defrosting of refrig eratorswhich comprises means for temporarily interrupting refrigeration, meansfor operating the interrupting means and adapted to be set in operationby manipulation of the refrigerator otherwise required for a use thereofin which continued refrigeration is desired, and means adapted fordelaying the operation of said operating means whereby a substantialperiod intervenes between said manipulation and the final effectiveinterruption of the refrigeration.

13. A device for defrosting refrigerators which comprises means forstoring energy, said means being associated with the refrigerator sothat its energy charge is renewed by a manipulation which is involved ina normal use of the refrigerator, means operated by said stored energyfor temporarily interrupting normal refrigeration, and means for socontrolling the release of the stored energy that said interruptingmeans will not be operated to the point of interrupting refrigerationuntil after a predetermined delay following said renewal of the energycharge.

14. The combination with an automatic refrigerator comprising arefrigerating device, a freezing container associated therewith, athermostatic control for the refrigeration device, and an insulating boxhaving a door thereon, of means for automatically initiating adefrosting period, means responsive to movement of the door and adaptedto prevent initiating of the defrosting period by said first-named meansduring a period sufficient normally to freeze ice in said container.

15. The combination with an automatic refrigerator comprising arefrigerating device, a freezing container associated therewith, and aninsulated box containing the cold unit of the refrigerating device andthe freezing container, of means for temporarily interrupting operationof the refrigeration device during a period adapted to permit melting offrost accumulated on the refrigerating device and means responsive touse of the refrigerator involving the placing in said container ofliquid to be frozen, adapted to delay the eifect of said interruptingmeans during a period following said use while such liquid is freezing.

16. An automatic defrosting mechanism for mechanical refrigeratorsincluding means operable at a predetermined interval after the closingof the refrigerator door to cut out the refrigerating unit, and means tocut in the refrigerating unit when defrosting is completed.

17. A control device for a refrigerator including means operative tomodify normal operation of the refrigerator to permit melting of frostthereon, and appreciably later than when said means is placed in itsinitial operative condition, and means for intermittently placing saidfirst means in its initial operative condition, whereby modifiedoperation of the refrigerator is efiected only when a period betweenoperation of said second means exceeds the time delay period of saidfirst means.

18. In a refrigerator having a door, a control device including meansoperative to modify normal operation of the refrigerator to permitmelting of frost thereon, and appreciably later than when said means isplaced in its initial operative condition, and means for intermittentlyplacing said first means in its initial operative condition each timesaid door is opened, whereby modified operation of the refrigerator iseffected only when a period between door opening operations exceeds thetime delay period of said first means.

19. The combination with an insulating box having an access opening, aclosure therefor and refrigerating apparatus including an evaporatorwithin the box, of means for suspending the operation of said apparatusto allow defrosting of said evaporator, and mechanism for delaying theoperation of said suspending means for periods of time sufiicient topermit a normally required amount of refrigeration to be effected bysaid apparatus, said mechanism including means for starting a period ofdelay, said last-named means being actuated in response to a use of thebox including at least one operation of the closure.

TRUE/IAN S. SAFFORD.

